Application of force feedback on an input device to urge its operator to command an articulated instrument to a preferred pose

ABSTRACT

A medical robotic system includes an entry guide with articulated instruments extending out of its distal end. A controller is configured to command manipulation an articulated instrument in response to operator manipulation of an associated input device while generating a force command to the input device that nudges the operator to command the instrument to a preferred pose. When a transition is to occur between first and second preferred poses, one is phased in while the other is phased out. Virtual barriers may be imposed to prevent the articulated instrument from being commanded to an undesirable pose.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/296,488 (filed Oct. 18, 2016), which is a divisional of U.S.application Ser. No. 13/292,760 (filed Nov. 9, 2011), now U.S. Pat. No.9,492,927, which is a continuation-in-part to U.S. application Ser. No.12/704,669 (filed Feb. 12, 2010), now U.S. Pat. No. 8,918,211, each ofwhich is incorporated herein by reference.

U.S. application Ser. No. 13/292,760 (filed Nov. 9, 2011) is also acontinuation-in-part to U.S. application Ser. No. 12/613,328 (filed Nov.5, 2009), now U.S. Pat. No. 9,084,623, which is a continuation-in-partto U.S. application Ser. No. 12/541,913 (filed Aug. 15, 2009), now U.S.Pat. No. 8,903,546, each of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention generally relates to medical robotic systems andin particular, to a method and system applying force feedback on aninput device to urge its operator to command an articulated instrumentto a preferred pose.

BACKGROUND

Medical robotic systems such as teleoperative systems used in performingminimally invasive surgical procedures offer many benefits overtraditional open surgery techniques, including less pain, shorterhospital stays, quicker return to normal activities, minimal scarring,reduced recovery time, and less injury to tissue. Consequently, demandfor such medical robotic systems is strong and growing.

One example of such a medical robotic system is the DA VINCI® SurgicalSystem from Intuitive Surgical, Inc., of Sunnyvale, Calif., which is aminimally invasive robotic surgical system. The DA VINCI® SurgicalSystem has a number of robotic arms that move attached medical devices,such as an image capturing device and Intuitive Surgical's proprietaryENDOWRIST® articulating surgical instruments, in response to movement ofinput devices by a surgeon viewing images captured by the imagecapturing device of a surgical site. Each of the medical devices isinserted through its own minimally invasive incision into the patientand positioned to perform a medical procedure at the surgical site. Theincisions are placed about the patient's body so that the surgicalinstruments may be used to cooperatively perform the medical procedureand the image capturing device may view it without their robotic armscolliding during the procedure.

To perform certain medical procedures, it may be advantageous to use asingle entry aperture, such as a minimally invasive incision or anatural body orifice, to enter a patient to perform a medical procedure.For example, an entry guide may first be inserted, positioned, and heldin place in the entry aperture. Articulated instruments such as anarticulated camera instrument and a plurality of articulated surgicaltool instruments, which are used to perform the medical procedure, maythen be inserted into a proximal end of the entry guide so as to extendout of its distal end. Thus, the entry guide accommodates a single entryaperture for multiple instruments while keeping the instruments bundledtogether as it guides them toward the work site.

A number of challenges arise in medical robotic systems using such abundled unit, however, because of the close proximity of the articulatedcamera and tool instruments. For example, because the camera instrumenthas proximal articulations (e.g., joints) that are not visible from thedistal tip camera view, the surgeon can lose track of the current stateof such articulations when moving the camera and consequently, theiravailable range of motion. Also, when the articulations of the cameraand tool instruments are out of view of the camera and therefore, notvisible to the surgeon through its captured images, the surgeon mayinadvertently drive links of the tools and/or camera instruments tocrash into one another while telerobotically moving the articulatedinstruments to perform a medical procedure. In either case, the safetyof the patient may be jeopardized and the successful and/or timelycompletion of the medical procedure may be adversely impacted.

OBJECTS AND SUMMARY

Accordingly, one object of one or more aspects of the present inventionis a medical robotic system, and method implemented therein, that urgesan operator to command a preferred pose for normal mode operation of anarticulated instrument, which serves as a biasing point for operatorcommanded movement of the articulated instrument during normal operationof the instrument.

Another object of one or more aspects of the present invention is amedical robotic system, and method implemented therein, that appliesforce feedback on an input device to urge its operator to command theposing of an articulated instrument to a preferred pose with smoothtransition to the preferred pose.

Another object of one or more aspects of the present invention is amedical robotic system, and method implemented therein, that appliesforce feedback on an input device to urge its operator to command theposing of an articulated instrument to a first preferred pose and thensmoothly transition to a second preferred pose according to anactivation signal.

These and additional objects are accomplished by the various aspects ofthe present invention, wherein embodiments of the invention aresummarized by the claims that follow below.

Additional objects, features and advantages of the various aspects ofthe present invention will become apparent from the followingdescription of its preferred embodiment, which description should betaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of a medical robotic system utilizingaspects of the present invention.

FIG. 2 illustrates a perspective view of a distal end of an entry guidewith a plurality of articulated instruments extending out of it in amedical robotic system utilizing aspects of the present invention.

FIGS. 3-4 respectively illustrate top and right side views ofarticulated instruments extending out of a distal end of an entry guidein a medical robotic system utilizing aspects of the present invention.

FIG. 5 illustrates a block diagram of interacting components of anarticulated instrument manipulator and an articulated instrument as usedin a medical robotic system utilizing aspects of the present invention.

FIG. 6 illustrates a block diagram of an instrument controller foroperator commanded movement of an articulated instrument in a medicalrobotic system utilizing aspects of the present invention.

FIG. 7 illustrates a side view of an articulated instrument extendingout of a distal end of an entry guide in a preferred pose for normaloperation as used in a medical robotic system utilizing aspects of thepresent invention.

FIG. 8 illustrates a side view of an articulated instrument extendingout of a distal end of an entry guide in a preferred pose for retractionback into the entry guide as used in a medical robotic system utilizingaspects of the present invention.

FIG. 9 illustrates a block diagram of a simulated instrument block ofthe instrument controller of FIG. 6 as used in a medical robotic systemutilizing aspects of the present invention.

FIG. 10 illustrates a block diagram of pose data and pose nudging blocksof the instrument controller of FIG. 6 as used in a medical roboticsystem utilizing aspects of the present invention.

FIG. 11 illustrates activation signals for normal mode operation andretraction mode as a function of time as used in a medical roboticsystem utilizing aspects of the present invention.

FIG. 12 illustrates a block diagram of the retraction mode nudging blockof FIG. 10 as used in a medical robotic system utilizing aspects of thepresent invention.

FIG. 13 illustrates a block diagram of the normal mode nudging block ofFIG. 10 as used in a medical robotic system utilizing aspects of thepresent invention.

FIG. 14 illustrates a block diagram of the force converter block ofFIGS. 12 and 13 as used in a medical robotic system utilizing aspects ofthe present invention.

FIG. 15 illustrates a flow diagram of a method for modifying a commandedpose of an articulated instrument by applying a virtual barrier as aconstraint as usable in a method for urging operator manipulation of aninput device to command the articulated instrument to a preferred poseutilizing aspects of the present invention.

FIG. 16 illustrates a flow diagram of a method for generating aretraction mode activation signal usable in a method for urging operatormanipulation of an input device to command the articulated instrument toa preferred pose utilizing aspects of the present invention.

FIG. 17 illustrates a flow diagram of a method for generating a normalmode deactivation signal usable in a method for urging operatormanipulation of an input device to command the articulated instrument toa preferred pose utilizing aspects of the present invention.

FIG. 18 illustrates a flow diagram of a first embodiment of a method forurging operator manipulation of an input device to command anarticulated instrument to a preferred pose utilizing aspects of thepresent invention.

FIG. 19 illustrates a flow diagram of a second embodiment of a methodfor urging operator manipulation of an input device to command anarticulated instrument to a preferred pose utilizing aspects of thepresent invention.

FIG. 20 illustrates a flow diagram of a third embodiment of a method forurging operator manipulation of an input device to command anarticulated instrument to a preferred pose utilizing aspects of thepresent invention.

FIG. 21 illustrates a flow diagram of a fourth embodiment of a methodfor urging operator manipulation of an input device to command anarticulated instrument to a preferred pose utilizing aspects of thepresent invention.

FIG. 22 illustrates a block diagram of an alternative instrumentcontroller for operator commanded movement of an articulated instrumentin a medical robotic system utilizing aspects of the present invention.

FIG. 23 illustrates a block diagram of a “phase-in” nudging blockproviding a first nudging force command which is to be phased-in as aforce to be applied against an input control device, as used in amedical robotic system utilizing aspects of the present invention.

FIG. 24 illustrates a block diagram of a “phase-out” nudging blockproviding a second nudging force command which is to be phased-out as aforce being applied against an input control device, as used in amedical robotic system utilizing aspects of the present invention.

DETAILED DESCRIPTION

FIG. 1 illustrates a block diagram of a medical robotic system 100. Anentry guide (EG) 200 is configured to be inserted through an entryaperture such as a minimally invasive incision or a natural body orificein a Patient. Articulated instruments such as a first articulatedsurgical tool (TOOL1) 231, second articulated surgical tool (TOOL2) 241,and an articulated stereo camera (CAM) 211 may be inserted through andextend out of a distal end of the entry guide 200. As shown in FIG. 2,the camera 211 has a stereo pair of image capturing devices 311, 312 anda fiber optic cable 313 (coupled at its proximal end to a light source)housed in its tip. The surgical tools 231, 241 have end effectors 331,341. Although only two tools 231, 241 are shown, the entry guide 200 mayguide additional tools as required for performing a medical procedure ata work site in the Patient. Additional details on the articulatedinstruments 211, 231, 241 are provided in reference to FIGS. 3 and 4below.

Each of the devices 231, 241, 211, 200 is manipulated and controlled byits own manipulator and controller. In particular, the articulatedcamera instrument 211 is manipulated by a camera manipulator (ECM) 212which is controlled by camera instrument controller (CTRLC) 213, thefirst articulated surgical tool 231 is manipulated by a first toolmanipulator (PSM1) 232 which is controlled by tool instrument controller(CTRL1) 233, the second articulated surgical tool 241 is manipulated bya second tool manipulator (PSM2) 242 which is controlled by toolinstrument controller (CTRL2) 243, and the entry guide 200 ismanipulated by an entry guide manipulator (EGM) 202 which is controlledby entry guide controller (CTRLG) 203. The controllers 203, 233, 243,213 are implemented in processor 102 as master/slave control systems asdescribed in reference to FIG. 6 below.

Each of the articulated instrument manipulators 232, 242, 212 is amechanical assembly that carries actuators and provides a mechanical,sterile interface to transmit motion to its respective articulatedinstrument. Each articulated instrument 231, 241, 211 is a mechanicalassembly that receives the motion from its manipulator and, by means ofa cable transmission, propagates it to the distal articulations (e.g.,joints). Such joints may be prismatic (e.g., linear motion) orrotational (e.g., they pivot about a mechanical axis). Furthermore, theinstrument may have internal mechanical constraints (e.g., cables,gearing, cams and belts, etc.) that force multiple joints to movetogether in a pre-determined fashion. Each set of mechanicallyconstrained joints implements a specific axis of motion, and constraintsmay be devised to pair rotational joints (e.g., joggle joints). Notealso that in this way the instrument may have more joints than theavailable actuators.

The entry guide manipulator (EGM) 202 is usable to robotically insertand retract the entry guide 200 into and out of the entry aperture. Itmay also be used to robotically pivot the entry guide 200 in pitch, rolland yaw relative to a longitudinal axis of the entry guide 200 about apivot point (also referred to as a remote center “RC”). A setup arm maybe used to hold and position the entry guide 200 so that its remotecenter RC is positioned at the entry aperture.

Two input devices 108, 109 are provided for manipulation by a Surgeon.Each of the input devices 108, 109 may be selectively associated withone of the devices 211, 231, 241, 200 so that the associated device maybe controlled by the input device through its controller andmanipulator. The Surgeon (or an Assistant) may perform such selection ina conventional manner, such as interacting with a menu on a GraphicalUser Interface (GUI), providing voice commands recognized by a voicerecognition system, inputting such associations into the system 100using an input device such as a touchpad, or interacting with specialpurpose buttons provided on the input devices 108, 109. Using any one ofsuch association mechanisms, a select input is generated and provided toa multiplexer (MUX) 280, which is implemented in the processor 102. Thevalue of the select input (e.g., combination of l's and 0's) indicateswhich association (i.e., cross-switching) is selected.

For example, a first value for the select input to the multiplexer 280places the left and right input devices 108, 109 in “tool followingmodes” wherein they are respectively associated with the first andsecond surgical tools 241, 231 so the Surgeon may perform a medicalprocedure on the Patient while the entry guide 200 is locked in place.In this configuration, the multiplexer 280 cross-switches torespectively connect output and input 251, 252 of the input device 108to input and output 260, 261 of the tool controller 243; andrespectively connect output and input 253, 254 of the input device 109to input and output 268, 269 of the tool controller 233.

When the camera 211 is to be repositioned by the Surgeon, either one orboth of the left and right input devices 108, 109 may be associated withthe camera 211 using a second value for the select input so that theSurgeon may move the camera 211 through its controller 213 andmanipulator 212. Similarly, when the entry guide 200 is to berepositioned by the Surgeon, either one or both of the left and rightinput devices 108, 109 may be associated with the entry guide 200 usinga third value for the select input so that the Surgeon may move theentry guide 200 through its controller 203 and manipulator 202. In anycase, disassociated devices are soft-locked in place by its respectivecontroller.

The images captured by the camera instrument 211 are processed by animage processor 214 and displayed on a display screen 104 so as toprovide a telepresence experience to the Surgeon, as described forexample in U.S. Pat. No. 6,671,581 “Camera Referenced Control in aMinimally Invasive Surgical Apparatus,” which is incorporated herein byreference. Thus, a Surgeon using the medical robotic system 100 mayperform a medical procedure on the Patient by manipulating input devices108, 109 to cause corresponding movement of associated surgical tools231, 241 while the Surgeon views images of the work site on the displayscreen 104.

Although described as a processor, it is to be appreciated that theprocessor 102 may be implemented in practice by any combination ofhardware, software and firmware. Also, its functions as described hereinmay be performed by one unit or divided up among different components,each of which may be implemented in turn by any combination of hardware,software and firmware distributed throughout the system.

For additional details on the construction and operation of generalaspects of a medical robotic system such as described herein, see, e.g.,U.S. Pat. No. 6,493,608 “Aspects of a Control System of a MinimallyInvasive Surgical Apparatus,” and U.S. Pat. Application Pub. No. U.S.2008/007129 “Minimally Invasive Surgical System,” which are incorporatedherein by reference.

FIGS. 3-4 respectively illustrate, as examples, top and right side viewsof a distal end of the entry guide 200 with the articulated camerainstrument 211 and articulated surgical tool instruments 231, 241extending outward. The articulated camera 211 extends through passage321 and the articulated surgical tools 231, 241 respectively extendthrough passages 431, 441 of the entry guide 200. The camera 211includes a tip 311, first, second, and third links 322, 324, 326, firstand second joint assemblies (also referred to herein simply as “joints”)323, 325, and a wrist assembly 327. The first joint assembly 323 couplesthe first and second links 322, 324 and the second joint assembly 325couples the second and third links 324, 326 so that the second link 324may pivot about the first joint assembly 323 in pitch and yaw while thefirst and third links 322, 326 remain parallel to each other.

The first and second joints 323, 325 are referred to as “joggle joints”,because they cooperatively operate together so that as the second link324 pivots about the first joint 323 in pitch and/or yaw, the third link326 pivots about the second joint 325 in a complementary fashion so thatthe first and third links 322, 326 always remain parallel to each other.The first link 322 may also rotate around its longitudinal axis in rollas well as move in and out (e.g., insertion towards the work site andretraction from the worksite) through the passage 321. The wristassembly 327 also has pitch and yaw angular movement capability so thatthe camera's tip 311 may be oriented up or down and to the right orleft, and combinations thereof.

The joints and links of the tools 231, 241 are similar in constructionand operation to those of the camera 211. In particular, the tool 231includes an end effector 331 (having jaws 338, 339), first, second, andthird links 332, 334, 336, first and second joint assemblies 333, 335,and a wrist assembly 337 that are driven by actuators such as describedin reference to FIG. 5 (plus an additional actuator for actuating theend effector 331). Likewise, the tool 241 includes an end effector 341(having jaws 348, 349), first, second, and third links 342, 344, 346,first and second joint assemblies 343,345, and a wrist assembly 347 thatare also driven by actuators such as described in reference to FIG. 5(plus an additional actuator for actuating the end effector 341).

FIG. 5 illustrates, as an example, a diagram of interacting parts of anarticulated instrument (such as the articulated camera 211 and thearticulated surgical tools 231, 241) and its corresponding instrumentmanipulator (such as the camera manipulator 212 and the toolmanipulators 232, 242). Each of the instruments includes a number ofactuatable assemblies 521-523, 531-533, 570 for effectuating movement ofthe instrument (including its end effector), and its correspondingmanipulator includes a number of actuators 501-503, 511-513, 560 foractuating the actuatable assemblies.

In addition, a number of interface mechanisms may also be provided. Forexample, pitch/yaw coupling mechanisms 540, 550 (respectively for thejoggle joint pitch/yaw and the wrist pitch/yaw) and gear ratios 545, 555(respectively for the instrument roll and the end effector actuation)are provided in a sterile manipulator/instrument interface to achievethe required range of motion of the instrument joints in instrumentjoint space while both satisfying compactness constraints in themanipulator actuator space and preserving accurate transmissions ofmotion across the interface. Although shown as a single block 540, thecoupling between the joggle joint actuators 501, 502 (differentiated as#1 and #2) and joggle joint pitch/yaw assemblies 521, 522 may include apair of coupling mechanisms—one on each side of the sterile interface(i.e., one on the manipulator side of the interface and one on theinstrument side of the interface). Likewise, although shown as a singleblock 550, the coupling between the wrist actuators 512, 513(differentiated as #1 and #2) and wrist pitch/yaw joint assemblies 532,533 may also comprise a pair of coupling mechanisms—one on each side ofthe sterile interface.

Both the joggle joint pitch assembly 521 and the joggle joint yawassembly 522 share the first, second and third links (e.g., links 322,324, 326 of the articulated camera 211) and the first and second joints(e.g., joints 322, 325 of the articulated camera 211). In addition tothese shared components, the joggle joint pitch and yaw assemblies 521,522 also include mechanical couplings that couple the first and secondjoints (through joggle coupling 540) to the joggle joint pitch and yawactuators 501, 502 so that the second link may controllably pivot abouta line passing through the first joint and along an axis that islatitudinal to the longitudinal axis of the first link (e.g., link 322of the articulated camera 211) and the second link may controllablypivot about a line passing through the first joint and along an axisthat is orthogonal to both the latitudinal and longitudinal axes of thefirst link.

The in/out (I/O) assembly 523 includes the first link (e.g., link 322 ofthe articulated camera 211) and interfaces through a drive traincoupling the in/out (I/O) actuator 503 to the first link so that thefirst link is controllably moved linearly along its longitudinal axis byactuation of the I/O actuator 503. The roll assembly 531 includes thefirst link and interfaces through one or more gears (i.e., having thegear ratio 545) that couple a rotating element of the roll actuator 511(such as a rotor of a motor) to the first link so that the first link iscontrollably rotated about its longitudinal axis by actuation of theroll actuator 511.

The instrument manipulator (e.g., camera manipulator 212) includes wristactuators 512, 513 that actuate through wrist coupling 550 pitch and yawjoints 532, 533 of the wrist assembly (e.g., wrist assembly 327 of thearticulated camera 211) so as to cause the instrument tip (e.g., cameratip 311) to controllably pivot in an up-down (i.e., pitch) andside-to-side (i.e., yaw) directions relative to the wrist assembly. Thegrip assembly 570 includes the end effector (e.g., end effector 331 ofthe surgical tool 231) and interfaces through one or more gears (i.e.,having the gear ratio 555) that couple the grip actuator 560 to the endeffector so as to controllably actuate the end effector.

The group of instrument joints 500 is referred to as “translationaljoints” because by actuation of a combination of these joints, theinstrument's wrist assembly may be positioned translationally withinthree-dimensional space using arc compensation as needed. The group ofinstrument joints 510 is referred to as “orientational joints” becauseby actuation of these joints, the instrument's tip may be oriented aboutthe wrist assembly.

At various stages before, during, and after the performance of a medicalprocedure, there may be preferred poses for the articulated instruments211, 231, 241 to best accomplish tasks performed at the time. Forexample, during normal operation, as shown in FIGS. 3 and 4, a preferredpose for each of the surgical tools 231, 241 may be an “elbow out, wristin” pose to provide good range of motion while minimizing chances ofinadvertent collisions with other instruments. Likewise, during normaloperation, as shown in FIGS. 3 and 4, a preferred pose for the camerainstrument 211 may be a “cobra” pose in which a good view of the endeffectors 331, 341 of the surgical tool instruments 231, 241 is providedat the camera's image capturing end. As another example, when it isdesired to retract an instrument back into the entry guide 200 toperform a tool exchange (i.e., exchange the instrument or its endeffector for another instrument or end effector) or for reorienting theentry guide 200 by pivoting it about its remote center, a preferred posefor the instrument prior to its retraction into the entry guide 200 is a“straightened” pose wherein the links of the instrument are aligned in astraight line such as shown in FIG. 8.

FIG. 6 illustrates, as an example, a block diagram of the camerainstrument controller (CTRLC) 213, which controls the posing (i.e., bothtranslationally and orientationally) of the articulated camerainstrument 211 as commanded by movement of the input device 108 by theSurgeon, when the input device 108 is selectively associated with thecamera instrument 211 through the multiplexer 280 as previouslydescribed in reference to FIG. 1. The input device 108 includes a numberof links connected by joints so as to facilitate multipledegrees-of-freedom movement. For example, as the Surgeon/operator movesthe input device 108 from one position to another, sensors associatedwith the joints of the input device 108 sense such movement at samplingintervals (appropriate for the processing speed of the processor 102 andcamera control purposes) and provide digital information 631 indicatingsuch sampled movement in joint space to input processing block 610.

Input processing block 610 processes the information 631 received fromthe joint sensors of the input device 108 to transform the informationinto corresponding desired positions and velocities for the camerainstrument 211 in its Cartesian space relative to a reference frameassociated with the position of the Surgeon's eyes (the “eye referenceframe”) by computing joint velocities from the joint positioninformation and performing the transformation using a Jacobian matrixand eye related information using well-known transformation techniques.

Scale and offset processing block 601 receives the processed information611 from the input processing block 610 and applies scale and offsetadjustments to the information so that the resulting movement of thecamera instrument 211 and consequently, the image being viewed on thedisplay screen 104 appears natural and as expected by the operator ofthe input device 108. The scale adjustment is useful where smallmovements of the camera instrument 211 are desired relative to largermovements of the input device 108 in order to allow more precisemovement of the camera instrument 211 as it views the work site. Inaddition, offset adjustments are applied for aligning the input device108 with respect to the Surgeon's eyes as he or she manipulates theinput device 108 to command movement of the camera instrument 211 andconsequently, its captured image that is being displayed at the time onthe display screen 104.

A simulated instrument block 604 transforms the commanded pose 621 ofthe camera instrument 211 from its Cartesian space to its joint spaceusing inverse kinematics, limiting the commanded joint positions andvelocities to avoid physical limitations or other constraints such asavoiding harmful contact with tissue or other parts of the Patient, andapplying virtual constraints that may be defined to improve theperformance of a medical procedure being performed at the time by theSurgeon using the medical robotic system 100. In particular, asillustrated in FIG. 9, the commanded pose 621 may be modified by virtualbarrier logic 901 (described in more detail in reference to FIG. 15below) which implements a virtual constraint on the commanded pose 621to generate a modified commanded pose 623. Inverse kinematics andlimiting block 902 then converts the modified commanded pose 623 frominstrument Cartesian space to instrument joint space and limits thejoint position and/or velocity to physical limitations or otherconstraints associated with or placed on the joints of the articulatedcamera instrument 211.

The output 622 of the simulated instrument block 604 (which includes acommanded value for each joint of the camera instrument 211) is providedto a joint control block 605 and a forward kinematics block 606. Thejoint controller block 605 includes a joint control system for eachcontrolled joint (or operatively coupled joints such as “joggle joints”)of the camera instrument 211. For feedback control purposes, sensorsassociated with each of the controlled joints of the camera instrument211 provide sensor data 632 back to the joint control block 605indicating the current position and/or velocity of each joint of thecamera instrument 211. The sensors may sense this joint informationeither directly (e.g., from the joint on the camera instrument 211) orindirectly (e.g., from the actuator in the camera manipulator 212driving the joint). Each joint control system in the joint control block605 then generates torque commands 633 for its respective actuator inthe camera manipulator 212 so as to drive the difference between thecommanded and sensed joint values to zero in a conventional feedbackcontrol system manner.

The forward kinematics block 606 transforms the output 622 of thesimulated instrument block 604 from the camera instrument's joint spaceback to Cartesian space relative to the eye reference frame usingforward kinematics of the camera instrument 211. The output 641 of theforward kinematics block 606 is provided to the scale and offsetprocessing block 601 as well as back to the simulated instrument block604 for its internal computational purposes.

The scale and offset processing block 601 performs inverse scale andoffset functions on the output 641 of the forward kinematics block 606before passing its output 612 to the input processing block 610 where anerror value is calculated between its output 611 and input 612. If nolimitation or other constraint had been imposed on the input 621 to thesimulated instrument block 604, then the calculated error value would bezero. On the other hand, if a limitation or constraint had been imposed,then the error value is not zero and it is converted to a torque command634 that drives actuators in the input device 108 to provide forcefeedback felt by the hands of the Surgeon. Thus, the Surgeon becomesaware that a limitation or constraint is being imposed by the force thathe or she feels resisting his or her movement of the input device 108 inthat direction.

A pose nudging block 625 is included in the controller 213 to generate anudging force command 627 which is provided to the input processingblock 610. The input processing block 610 then converts the nudgingforce command 627 into motor torques so that the commanded nudging forceis felt by the Surgeon on the input device 108 in a manner that urgesthe Surgeon to command the pose of the camera instrument 211 to apreferred pose provided in pose data 626.

For the camera instrument 211, there may be at least two preferredposes. During normal mode operation, such as when the Surgeon isperforming a medical procedure on a Patient, the preferred pose for thecamera instrument 211 is the “cobra” pose shown in FIGS. 3 and 4.Looking downward at the “cobra” pose in FIG. 3, all links 322, 324, 326of the camera instrument 211 are aligned with the longitudinal axis 401of the first link 322 so that they have maximum available range oflateral motion and provide a reference for the main insertion directionof the camera instrument 211. Further, the joggle joints 323, 325 are“joggled up”, as shown in FIG. 4, so that the third link 326 isdisplaced a distance above the longitudinal axis 401 and the wristassembly 327 is rotated at a negative pitch angle so that the camera tip311 is oriented downwards at an angle so that the camera is preferablyviewing the center of a workspace for the end effectors 331 and 341 oftool instruments 231 and 241, which are also extending out of the distalend of the entry guide 200 at the time. In this case, the Surgeon ispreferably allowed to freely move the camera 211 forward and backward inthe input/output (I/O) direction along the longitudinal axis 401 so thatthe camera 211 may better view the end effectors 331, 341 as they moveaway from and back towards the distal end of the entry guide 200 duringtheir use.

During retraction mode, the preferred pose for the camera instrument 211is the “straightened” pose. FIGS. 7 and 8 respectively illustratesimplified side views of the camera instrument 211 in the “cobra” and“straightened” poses. To go from the “cobra” pose to the “straightened”pose, the joggle joints 323, 325 rotate link 324 until it is alignedwith the longitudinal axis 401 of the first link 322. Since the link 326is always parallel to the first link 322 due to operation of the jogglejoints 323, 325, when the link 324 is aligned with the longitudinal axis401, the link 326 also is aligned with the longitudinal axis 401.Meanwhile, the wrist joint 327 also rotates the camera tip 311 until itscentral axis also aligns with the longitudinal axis 401.

FIG. 10 illustrates, as an example, a block diagram of the pose nudgingblock 625 and its coupling to the pose data block 626. In this example,the pose data block 626 comprises data stored in a non-volatile memorywhich is accessible to the processor 102. The stored data for the camerainstrument 211 includes data for the “straightened” pose 1001 which isused for retraction of the camera instrument 211 and data for the“cobra” pose 1002 which is used during normal mode operation of thecamera instrument 211.

The pose nudging block 625 comprises a retraction mode nudging block1003, a normal mode nudging block 1004, and a summing node 1005. A keyfeature of the retraction and normal mode nudging blocks 1003 and 1004is that nudging force commands from one is phased in while nudging forcecommands from the other is being phased out during a transition period.A more detailed description of the retraction mode nudging block 1003 isdescribed in reference to FIG. 12 below and a more detailed descriptionof the normal mode nudging block 1004 is described in reference to FIG.13.

FIG. 12 illustrates, as an example, a block diagram of the retractionmode nudging block 1003 which continually processes incoming data. Asumming node 1201 computes a difference (XERR, VERR) between thepreferred “straightened” pose 1001 (i.e., the retraction configurationfor the camera instrument 211) and the modified commanded pose (XSLV,VSLV) 623 which is generated by the virtual barrier logic 901 of thesimulated instrument block 608 of the instrument controller 213. As usedherein, the term “pose” means both position and orientation of theinstrument as well as their positional and rotational velocities, sothat the commanded pose may include both positional (XCMD) and velocity(VCMD) components, the modified commanded pose may include bothpositional (XSLV) and velocity (VSLV) components, the preferred pose mayinclude both positional (XPP) and velocity (VPP) components, and thecomputed difference between the preferred pose and the modifiedcommanded pose may include both positional (XERR) and velocity (VERR)components. In the computation performed in summing node 1201, however,the velocity (VPP) components of the preferred pose (VPP) are allpresumed to be zero.

To explain how the modified commanded pose (XSLV, VSLV) is generated, anexample of the virtual barrier logic 901 is described in reference toFIG. 15. In block 1501, the logic 901 receives the commanded pose (XCMD)621 from the scale and offset block 621 and in block 1502, it determinesthe projection of the commanded pose 621 in a first direction, which inthe present example is the instrument retraction direction along thelongitudinal axis 401 of the first link 322 of the camera instrument211. In block 1503, a determination is made whether the projection alongthe first direction would command the camera instrument 211 to movebeyond a virtual barrier position. The virtual barrier position in thiscase is a position along the longitudinal axis 401 which is a thresholddistance or safety margin from the distal end of the entry guide 200. Asdescribed in US 2011/0040305 A1, the purpose of the safety margin is toprevent damage from occurring to either or both the entry guide 200 andthe articulated instrument 211 when attempting to force the articulatedinstrument 211 back into the entry guide 200 while it is in aconfiguration in which it physically will not fit at the time. If thedetermination in block 1503 is NO, then the virtual barrier logic 901jumps back to block 1501 to process data for a next process cycle. Onthe other hand, if the determination in block 1503 is YES, then in block1504, the current pose of the camera instrument 211 is determinedsensing its joint positions and applying forward kinematics to determinetheir corresponding Cartesian pose. In block 1505, a determination isthen made whether the current pose of the camera instrument 211 is thepreferred pose (i.e., “straightened” pose in this case). If thedetermination in block 1505 is YES, then the virtual barrier logic 901doesn't modify the commanded pose (XCMD) and jumps back to block 1501 toprocess data for a next process cycle. On the other hand, if thedetermination n block 1505 is NO, then commanded pose (XCMD) is modifiedby applying the virtual barrier as constraint so that the camerainstrument 211 is prevented from moving further in the first direction.The method then loops back to block 1501 to process data for the nextprocess cycle. Thus, the camera instrument 211 is prevented in this wayfrom moving beyond the virtual barrier position until the current poseis the preferred retraction pose of the camera instrument 211.

Referring back to FIG. 12, in block 1202, non-nudging components of thecalculated difference (XERR, VERR) are removed. In particular,translational components along the first direction and the rollrotational component about the tip 310 are removed since neither ofthese components affects the preferred pose (i.e., regardless of theirvalues, the camera instrument may be placed in a “straightened” pose asshown in FIG. 8). In block 1203, the modified difference (XERR′, VERR′)generated in block 1202 is converted to generate a force command thatwould result in one or more forces being applied to the input device 108so that the Surgeon is urged to command the camera instrument 211 to thepreferred pose. Preferably such force command is a visco-elastic sixdegree-of-freedom force that would be applied to correspondingdegrees-of-freedom of the input device 108.

An example of the force converter block 1203 is illustrated in FIG. 14by a block diagram of a Proportional-Derivative (PD) open loop system.In this PD system, the modified position difference (XERR′) ismultiplied by a position gain (KP) 1401 and limited by limiter 1402 to afirst saturation value (SATP) to generate a first force commandcontribution. At the same time, the modified velocity difference (VERR′)is multiplied by a derivative gain (KD) 1403 to generate a second forcecommand contribution. A summing node 1404 calculates a differencebetween second and first force command contributions and a limiter 1405limits to the difference to a second saturation value (SATF). The thuslimited difference between the second and first force commandcontributions results in a visco-elastic six degree-of-freedom Cartesianforce for nudging the Surgeon to move the input device 108 so as tocommand the preferred pose. Values for the first and second saturationvalues are selected so as to ensure that commanded motor torques on themotors of the input device 108 do not exceed their rated maximum values.

Referring back to FIG. 12, modulator 1207 amplitude modulates thevisco-elastic six degree-of-freedom Cartesian force generated by theforce converter block 1203 with a retraction activation signal whichresembles curve 1101 in FIG. 11. To generate the retraction activationsignal, a summing node 1204 calculates a difference between thecommanded pose (XCMD) and the modified commanded pose (XSLV), ignoringvelocity contributions, modulation coefficients generator 1205 generatesa stream of modulation coefficients using the calculated difference, anda low-pass filter 1206 filters the stream of modulation coefficients.

An example of the generation of the retraction mode activation signal isprovided in a flow diagram illustrated in FIG. 16. Blocks 1601 and 1602describe actions taken by the summing node 1204. In particular, in block1601, the commanded pose (XCMD) and modified commanded pose (XSLV) arereceived, and in block 1602, a difference between the commanded pose(XCMD) and the modified commanded pose (XSLV) is calculated. Blocks 1603to 1607 next describe actions taken by the modulation coefficientsgenerator 1205. In block 1603, a projection of the calculated differencein a first direction (i.e., the retraction direction along thelongitudinal axis 401) is determined and in block 1604, a determinationis made whether the projection exceeds a threshold value. The thresholdvalue in this case should be large enough to ensure that the Surgeonreally intends to retract the camera instrument 211 and that it is notan inadvertent action such as may result from hand tremor. If thedetermination in block 1604 is YES, then in block 1605, the currentmodulation coefficient is set to an integer value “1”. On the otherhand, if the determination in block 1604 is NO, then in block 1606, thecurrent modulation coefficient is set to an integer value of “0”. Inblock 1607, the current modulation coefficient is then appended to astream of modulation coefficients generated in prior process periods.Block 1608 describes action taken by the low-pass filter 1206. Inparticular, in block 1608, the retraction activation signal is generatedby passing the stream of modulation coefficients through the low-passfilter 1206 and the process then jumps back to block 1601 to processdata for the next process cycle.

FIG. 13 illustrates, as an example, a block diagram of the normal modenudging block 1004 which also continually processes incoming data. Asumming node 1301 computes a difference (XERR, VERR) between thepreferred “cobra” pose 1002 (i.e., the normal mode configuration for thecamera instrument 211) and the modified commanded pose (XSLV, VSLV) 623which is generated by the virtual barrier logic 901 of the simulatedinstrument block 608 of the instrument controller 213.

In block 1302, non-nudging components of the calculated difference(XERR, VERR) are removed. In particular, translational components alongthe first direction and the roll rotational component about the tip 311are removed since neither of these components affects the preferred pose(i.e., regardless of their values, the camera instrument may be placedin a “cobra” pose as shown in FIG. 7). In block 1303, the modifieddifference (XERR′, VERR′) generated in block 1302 is converted togenerate a force command that would result in one or more forces beingapplied to the input device 108 so that the Surgeon is urged to commandthe camera instrument 211 to the preferred pose. Preferably such forcecommand is a visco-elastic six degree-of-freedom force that would beapplied to corresponding degrees-of-freedom of the input device 108,whose generation is similar to that previously described in reference toFIG. 14.

Modulator 1307 then amplitude modulates the visco-elastic sixdegree-of-freedom Cartesian force generated by the force converter block1303 with a normal mode deactivation signal which resembles curve 1102in FIG. 11. To generate the normal mode deactivation signal, a summingnode 1304 calculates a difference between the commanded pose (XCMD) andthe modified commanded pose (XSLV), ignoring velocity contributions,modulation coefficients generator 1305 generates a stream of modulationcoefficients using the calculated difference, and a low-pass filter 1306filters the stream of modulation coefficients.

An example of the generation of the normal mode deactivation signal isprovided in a flow diagram illustrated in FIG. 17. Blocks 1701 and 1702describe actions taken by the summing node 1304. In particular, in block1701, the commanded pose (XCMD) and modified commanded pose (XSLV) arereceived, and in block 1702, a difference between the commanded pose(XCMD) and the modified commanded pose (XSLV) is calculated. Blocks 1703to 1707 next describe actions taken by the modulation coefficientsgenerator 1305. In block 1703, a projection of the calculated differencein a first direction (i.e., the retraction direction along thelongitudinal axis 401) is determined and in block 1704, a determinationis made whether the projection exceeds a threshold value. The thresholdvalue in this case should be large enough to ensure that the Surgeonreally intends to retract the camera instrument 211 and that it is notinadvertent action such as may result from hand tremor. If thedetermination in block 1704 is YES, then in block 1705, the currentmodulation coefficient is set to an integer value “0”. On the otherhand, if the determination in block 1704 is NO, then in block 1706, thecurrent modulation coefficient is set to an integer value of “1”. Notethat the modulation coefficient value assignments are opposite to thoseused in the generation of the retraction activation signal, whichresults in one of the retraction and normal mode activation signalsphasing in while the other is phasing out. In block 1707, the currentmodulation coefficient is then appended to a stream of modulationcoefficients generated in prior process periods. Block 1708 finallydescribes action taken by the low-pass filter 1306. In particular, inblock 1708, the normal mode deactivation signal is generated by passingstream of modulation coefficients through the low-pass filter 1306. Theprocess then jumps back to block 1701 to process data for the nextprocess cycle.

The time constants for the low-pass filter 1206 in the retraction modenudging block 1003 and the low-pass filter 1306 in the normal modenudging block 1004 are preferably the same so that the phasing in andphasing out match during the transition period such as shown in FIG. 11,where time “t(k)” represents the time that the threshold valuedeterminations in blocks 1804 and 1704 first result in a YESdetermination, time “t(k−m)” represents a time prior to “t(k)” when thethreshold value determinations in blocks 1804 and 1704 resulted in a NOdetermination, and time “t(k+m)” represents a time after “t(k)” when thethreshold value determinations in blocks 1804 and 1704 still result in aYES determination.

FIG. 18 illustrates a flow diagram summarizing the first embodiment ofthe invention as described in detail above. In block 1801, a commandedpose (XCMD) is received from an input device associated at the time withthe articulated instrument whose pose is being commanded. In block 1802,the commanded pose is modified using virtual constraints (such asdescribed in reference to FIG. 15). In blocks 1803-1807, a first forcecommand is generated which is to be phased in to nudge the operator ofthe input device to command a first (new) preferred pose (such asdescribed in reference to FIG. 12) while concurrently in blocks1808-1812, a second force command is generated which is to be phased outto nudge the operator of the input device to command a second(incumbent) preferred pose (such as described in reference to FIG. 13).In block 1813, the first and second force commands are applied to theinput device so that initially the operator of the input device is urgedto command the second preferred pose then subsequently after a phasingin and phasing out transition period the operator is urged to commandthe first preferred pose.

FIGS. 19-21 illustrate additional embodiments of the invention whichinclude various combinations of some, but not all of the blocksdescribed in reference to FIG. 18. In particular, FIG. 19 illustrates asecond embodiment that is a modification to the first embodiment,wherein the commanded pose is not modified using virtual constraints bydeleting block 1802, but performing all other blocks of the firstembodiment. FIG. 20 illustrates a third embodiment that is amodification to the first embodiment, wherein a second (incumbent)preferred pose is not active by deleting blocks 808-812, but performingall other blocks of the first embodiment with block 813 modified sincethere is no second force command to be phased out. FIG. 21 illustrates afourth embodiment that is a modification to the third embodiment,wherein the commanded pose is not modified using virtual constraints bydeleting block 1802, but performing all other blocks of the thirdembodiment.

FIGS. 22-24 illustrate still other embodiments of the invention whichexpand upon some of the previously disclosed embodiments. In particular,whereas prior embodiments disclose a single preferred pose being activeat a time (outside a transition period), the embodiments shown in FIGS.22-24 contemplate the possibility of multiple preferred poses beingactive at a time with the active preferred poses being weighted so thatone or some may be more dominant than others. Further, the weightingsprovide an additional mechanism through which preferred poses may betransitioned in and out by making their respective weightingsdynamically alterable (e.g., progressively changing from a weighting of“0” to a weighting of “1” to phase the corresponding preferred pose inand conversely, progressively changing from a weighting of “1” to aweighting of “0” to phase the corresponding preferred pose out). Also,whereas prior embodiments disclose fixed preferred poses for differentoperating modes, the embodiments shown in FIGS. 22-24 contemplate thepossibility of dynamically changing preferred poses based upon systemdata such as the current or commanded poses of other articulatedinstruments. For example, the preferred pose for the camera instrument211 may dynamically change as the poses of the end effectors 331, 341 ofthe tool instruments 231, 241 change so that the end effectors 331, 341remain well positioned in a field of view of the camera instrument 211.As another example, the preferred poses of each of the articulatedinstruments 211, 231, 241 may dynamically change to avoid collisionswith others of the articulated instruments 211, 231, 241 during theperformance of a medical procedure using the articulated instruments211, 231, 241.

FIG. 22 illustrates, for example, a block diagram of an alternativeinstrument controller for operator commanded movement of an articulatedinstrument. Although the example is for the camera controller 213, it isto be appreciated that the same general structure may be used for otherdevice controllers 203, 233, 243 in the medical robotic system 100. Thefunctions of blocks 610, 601, 605, 606 are the same as previouslydescribed in reference to FIG. 6. The function of the simulatedinstrument block 2204 is generally the same as block 604 of FIG. 6 withregards to inverse kinematics and limiting, but may differ in regards tovirtual constraints imposed on the commanded pose 621 to generate amodified commanded pose 2205, because of different operating modesand/or preferred poses. Likewise, the function of pose nudging block2201 is generally the same as block 625 with regards to summing togethertwo pose nudging contributions wherein a first (new) preferred pose isto be phased in while a second (incumbent) preferred pose is to bephased out according to respective activation signals.

A pose generator block 2202 is included in the controller 213 todynamically generate one or more preferred poses that are provided tothe pose nudging block 2201, as well as pass through static preferredposes when appropriate. In particular, although a static preferred poseprovided by the pose data block 626 may be normally passed through, thepreferred pose for the articulated camera instrument 211 may dynamicallybe changed from the static preferred pose as conditions, such as theposes of other tool instruments 231, 241 around it, change. As oneexample, the preferred pose for the camera instrument 211 maydynamically change during normal operating mode to avoid collisions withthe tool instruments 231, 241, which are being used and therefore,moving at the time to perform a medical procedure on a patient anatomy.To dynamically generate one or more preferred poses to be phased in(such as preferred poses 2301, 2303, 2305 of FIG. 23) and one or morepreferred poses to be phased out (such as preferred poses 2401, 2403,2405), the pose generator block 2202 may use a different function of oneor more states of the system for each of the preferred poses to bedynamically changed. The system state information in this case isprovided by system data 2203. As one example, the system data 2203 maycomprise the commanded poses of other instruments 231, 241 in the system100. As another example, the system data 2203 may comprise the actualposes of the other instruments 231, 241 as determined by applyingforward kinematics to their sensed joint positions.

The pose nudging block 2201 includes “phase-in” and “phase-out” nudgingblocks which respectively generate nudging forces that are to bephased-in and phased-out on the input device 108 in a similar manner aspreviously described with respect to the retraction mode and normal modenudging blocks, 1003 and 1004, of FIG. 10.

FIG. 23 illustrates, as an example, a block diagram of the “phase-in”nudging block. A preferred pose 2320 is generated by a weighted averageof a plurality of preferred poses (e.g., preferred poses 2301, 2303,2305) so that each of the preferred poses is multiplied by acorresponding weight (e.g., weights 2302, 2304, 2306) with the sum ofthe weights equal to “1”. The weights may be fixed values or preferablydynamic values so one or more of the preferred poses may be dominant atdifferent times, in different operating modes or under different systemconditions. A difference between the preferred pose 2320 and themodified commanded pose 2205 is computed by summing node 2314.Non-nudging components of the difference are removed in block 2315 andthe result provided to force converter block 2316 which generates aforce command such as described in reference to block 1203 of FIG. 12. Aphase-in activation signal is generated by phase-in signal generatorblock 2317 so as to resemble the retraction mode activation signal 1101in FIG. 11. An amplitude modulated force command, which is to bephased-in on the input device 108, is then generated by amplitudemodulator 2318 by amplitude modulating the force command generated bythe force converter block 2316 with the phase-in activation signal.

Using a similar construction, FIG. 24 illustrates, as an example, ablock diagram of the “phase-out” nudging block. A preferred pose 2420 inthis case is generated by a weighted average of a plurality of preferredposes (e.g., preferred poses 2401, 2403, 2405) so that each of thepreferred poses is multiplied by a corresponding weight (e.g., weights2402, 2404, 2406) with the sum of the weights equal to “1”. The weightsmay be fixed values or preferably dynamic values so one or more of thepreferred poses may be dominant at different times, in differentoperating modes or under different system conditions. A differencebetween the preferred pose 2420 and the modified commanded pose 2205 iscomputed by summing node 2414. Non-nudging components of the differenceare removed in block 2415 and the result provided to force converterblock 2416 which generates a force command such as described inreference to block 1203 of FIG. 12. A phase-out activation signal isgenerated by phase-out signal generator block 2417 so as to resemble thenormal mode activation signal 1102 in FIG. 11. An amplitude modulatedforce command, which is provided to and is to be phased-out on the inputdevice 108, is then generated by amplitude modulator 2418 by amplitudemodulating the force command generated by the force converter block 2416with the phase-out activation signal.

In addition to the embodiments described herein, it is to be appreciatedthat other embodiments may be constructed, and are fully contemplated tobe within the scope of the present invention, through differentcombinations of their various teachings. In particular, although thevarious aspects of the present invention have been described withrespect to preferred and alternative embodiments, it will be understoodthat the invention is entitled to full protection within the full scopeof the appended claims.

What is claimed is:
 1. An instrument controller operatively coupleableto a master input device, a slave manipulator coupleable to anarticulated medical instrument, and a non-volatile memory storing dataindicating a plurality of preferred poses for the articulated medicalinstrument, the instrument controller comprising: an input processingunit configured to use a Jacobian to transform information received frommaster joint sensors of master joints of the master input device into adesired pose for the articulated medical instrument; a simulatedinstrument unit configured to use inverse kinematics to transforminformation of the desired pose for the articulated medical instrumentinto desired slave joint positions of the slave manipulator and thearticulated medical instrument; a joint control unit configured tocontrol actuation of slave joints of the slave manipulator and thearticulated medical instrument according to the desired slave jointpositions; and a pose nudging unit configured to receive informationindicative of a first preferred pose of the plurality of preferredposes, generate a nudging force command so as to be indicative of afirst difference between the desired pose for the articulated medicalinstrument and the first preferred pose, and provide the nudging forcecommand to the input processing unit, wherein the input processing unitis further configured to convert the nudging force command into commandsfor motors actuating the master joints of the master input device, andproviding the commands for the motors to the master input device.
 2. Theinstrument controller according to claim 1, wherein the first preferredpose corresponds to a first operating mode for the articulated medicalinstrument, wherein a second preferred pose of the plurality ofpreferred poses corresponds to a second operating mode for thearticulated medical instrument; and wherein the pose nudging unit isfurther configured to generate the nudging force command by: generatinga first nudging force command indicative of the first difference betweenthe desired pose for the articulated medical instrument and the firstpreferred pose, and using the first nudging force command as the nudgingforce command when the articulated medical instrument is operating inthe first operating mode; and generating a second nudging force commandindicative of a second difference between the desired pose for thearticulated medical instrument and the second preferred pose, and usingthe second nudging force command as the nudging force command when thearticulated medical instrument is operating in the second operatingmode.
 3. The instrument controller according to claim 2, wherein thepose nudging unit is further configured to generate the nudging forcecommand by phasing in the second nudging force command and phasing outthe first nudging force command when the articulated medical instrumentis transitioning from operating in the first operating mode to thesecond operating mode.
 4. The instrument controller according to claim3, wherein the pose nudging unit is further configured to generate thenudging force command by phasing in the second nudging force commandusing an activation signal and phasing out the first nudging forcecommand using a deactivation signal, wherein the activation signal andthe deactivation signal are complementary signals.
 5. The instrumentcontroller according to claim 2, wherein the articulated medicalinstrument is an articulated camera instrument, and wherein the firstpreferred pose is a pose from which working ends of other instrumentsare within a field of view of the articulated camera instrument during aperformance of a medical procedure.
 6. The instrument controlleraccording to claim 2, wherein the second preferred pose is a pose inwhich the articulated medical instrument is capable of being retractedinto an entry guide.
 7. The instrument controller according to claim 1,further comprising: a pose generator unit configured to generate theinformation indicative of the first preferred pose provided to the posenudging unit by: retrieving data indicating one of the plurality ofpreferred poses from the non-volatile memory according to at least oneof an instrument type of the articulated medical instrument and anoperating mode for the articulated medical instrument; and generatingthe first preferred pose by using the retrieved data.
 8. The instrumentcontroller according to claim 1, wherein the articulated medicalinstrument is an articulated camera instrument, the instrumentcontroller further comprising: a pose generator unit configured togenerate the information indicative of the first preferred pose providedto the pose nudging unit by: retrieving data indicating a staticpreferred pose from the non-volatile memory, wherein the staticpreferred pose is one of the plurality of preferred poses; anddynamically changing the static preferred pose so that at least one ofthe working ends of the other instruments remain positioned in a fieldof view of the articulated camera instrument during a performance of amedical procedure.
 9. The instrument controller according to claim 1,further comprising: a pose generator unit configured to generate theinformation indicative of the first preferred pose provided to the posenudging unit by: retrieving data indicating a static preferred pose fromthe non-volatile memory, wherein the static preferred pose is one of theplurality of preferred poses; and generating the first preferred pose bydynamically changing the static preferred pose so as to prevent acollision between the articulated medical instrument and anotherinstrument.
 10. The instrument controller according to claim 1, furthercomprising: a pose generator unit configured to generate the informationindicative of the first preferred pose provided to the pose nudging unitby: retrieving data indicating two or more preferred poses of theplurality of preferred poses from the non-volatile memory; andgenerating the first preferred pose by using a weighted average of thetwo or more preferred poses.
 11. The instrument controller according toclaim 1, wherein the input processing unit, the simulated instrumentunit, the joint control unit, and the pose nudging unit are implementedby a processor.
 12. A method for controlling movement of a slavemanipulator coupled to an articulated medical instrument in response tomovement of a master input device, while providing a nudging force onthe master input device to urge an operator of the master input deviceto command movement of the slave manipulator so that the articulatedmedical instrument moves towards a preferred pose, the methodcomprising: a processor using a Jacobian to transform informationreceived from joint sensors of master joints of the master input deviceinto a desired pose for the articulated medical instrument; theprocessor using inverse kinematics to transform information of thedesired pose for the articulated medical instrument into desired slavejoint positions of the slave manipulator and the articulated medicalinstrument; the processor controlling actuation of slave joints of theslave manipulator and the articulated medical instrument according tothe desired slave joint positions; the processor generating a nudgingforce command so as to be indicative of a first difference between thedesired pose for the articulated medical instrument and a firstpreferred pose of a plurality of preferred poses; the processorconverting the nudging force command into commands for motors actuatingthe master joints of the master input device; and the processorproviding the commands for the motors to the master input device. 13.The method according to claim 12, wherein the first preferred posecorresponds to a first operating mode for the articulated medicalinstrument, wherein a second preferred pose of the plurality ofpreferred poses corresponds to a second operating mode for thearticulated medical instrument; and wherein the processor generating anudging force command comprises: the processor generating a firstnudging force command indicative of the first difference between thedesired pose for the articulated medical instrument and the firstpreferred pose, and using the first nudging force command as the nudgingforce command when the articulated medical instrument is operating inthe first operating mode; and the processor generating a second nudgingforce command indicative of a second difference between the desired posefor the articulated medical instrument and the second preferred pose,and using the second nudging force command as the nudging force commandwhen the articulated medical instrument is operating in the secondoperating mode.
 14. The method according to claim 13, wherein theprocessor generating a nudging force command further comprises: theprocessor phasing in the second nudging force command and phasing outthe first nudging force command when the articulated medical instrumentis transitioning from operating in the first operating mode to thesecond operating mode.
 15. The method according to claim 14, wherein theprocessor phasing in the second nudging force command and phasing outthe first nudging force command comprises: the processor phasing in thesecond nudging force command using an activation signal; and theprocessor phasing out the first nudging force command using adeactivation signal, wherein the activation signal and the deactivationsignal are complementary signals.
 16. The method according to claim 13,wherein the articulated medical instrument is an articulated camerainstrument, and wherein the first preferred pose is a pose from whichworking ends of other instruments are within a field of view of thearticulated camera instrument during a performance of a medicalprocedure.
 17. The method according to claim 13, wherein the secondpreferred pose is a pose in which the articulated medical instrument iscapable of being retracted into an entry guide.
 18. The method accordingto claim 12, wherein the processor generating the information indicativeof the first preferred pose comprises: the processor retrieving dataindicating one of the plurality of preferred poses from non-volatilememory according to at least one of an instrument type of thearticulated medical instrument and an operating mode for the articulatedmedical instrument; and the processor generating the first preferredpose by using the retrieved data.
 19. The method according to claim 12,wherein the articulated medical instrument is an articulated camerainstrument, and wherein the processor generating the informationindicative of the first preferred pose comprises: the processorretrieving data indicating a static preferred pose from non-volatilememory, wherein the static preferred pose is one of the plurality ofpreferred poses; and the processor dynamically changing the staticpreferred pose so that at least one of the working ends of the otherinstruments remain positioned in a field of view of the articulatedcamera instrument during a performance of a medical procedure.
 20. Themethod according to claim 12, wherein the processor generating theinformation indicative of the first preferred pose comprises: theprocessor retrieving data indicating two or more preferred poses of theplurality of preferred poses from non-volatile memory; and the processorgenerating the first preferred pose by using a weighted average of thetwo or more preferred poses.